Arc-light electrode.



W. R. MOTT.

ARC LIGHT ELECTRODE.

APPLICATION FILED JUNE I3. I914.

& 1 9 1 9 2 h e F d e t U m .E. H 3 mm H5, U U L F U: U I H m TB F n- U S 1 ME M. i. 1 0 M w w m w mmEHE uEEEmmHnmm 7 1 1 PARTS [IF HAT-1E EARTH PLUUHIDE IN VEN TOR My w/yxm uflm M fl H.& M W W "ran sirurns rarnnr orrron 1 WILLIAM B. MOTT, or LAKEWOOD, onionssicnon To NATIONAL CARBON COMPANY,

A CORPORATION OF NEW JERSEY.

ARC-LIGHT ELECTRODE,

Application filed June 13, 1914,

-Lakewood, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Arc-Light Electrodes, of which the following is a full, clear, and exact description.

My invention relates to trodes of the flaming type, in which certain salts are incorporated to increase the candle power of the arc itself. Many different salts and other chemical compounds have been proposed or used for this purpose, the particular combination depending on the particular result to be attained.

The fluorids of the so-called rare earths are especially valuable as flaming materials where a white arc is desired, such as in photographic and photo-engraving work. On experimenting with many difierent combinations with such fluorids, I have found that the compounds of thorium have a marked effect on the luminosity, color and actinic property 'of the are when used in combination withthe rare earth fluorids in certain proportions.

Thorlum compounds, especially the oxids, fluorids and oxy-fluorids, are of extremely non-volatile character, and inasmuch as such materials are 'non-conducting-when cold, they have been considered to be of little use in arc electrodes since the insulating buttons of slag on the electrode ends prevent the starting of the are 'after the same have cooled sufliciently to be non-conducting. I have found that this slagging difiiculty of thorium compounds can be entirely overcome by combining them with the rare earth fluorids -up to a certain ratio. Above this ratio, the slagging difficulties are manifest at once, and an electrode having more than this percentage of a thorium. compound, is of very little value.

I have found that a thorium compound or compounds when used in conjunction with rare earth fluorids up to a certain percentage of the fluorids also greatly increases the candle power of the arc and intensifies its actinic property. Above this ratio, further increase of the thorium compound decreases the candle power. It is very fortunate that the limiting ratio as far as candle power in concerned is substantially identical with that relating' to the slagging diffiarc light elec- Spetification of Letters Patent.

and actinic power of used are of the carbon of the above table.

Patented Feb. 29, iaic.

, Serial No. 844,868.

so that the whiteness, candle power the arc can be greatly increased by the use of thorium compounds culty,

uptoa certain ratio Without encountering any slagging diificulties, such difficulties only appearing'when the ratio .of thorium content to fiuorid content is such as to cause a decrease in candle power.

The particular electrodes with which the fluorids and thorium compounds have been type in which the carbon forms the conducting body of the electrode, although it would be possible to use other conducting bodies if desired. For all purposes, however, carbon is the best conducting body at present-known.

The table below gives the data of electrodes containing varying amounts of rare earth fluorid and thorium fluorid, the efficiency of the various combinations being shown by the rating in average photographic power, 'and the slagging tendency is indicated at the bottom of each column.

Rare earth fluorid. 60 50 40 30' 20 10 0 Thorium fluorid... 0 10 20 30 40 50 60 Core black 40 40 40v 40 40 40 40 Avera e -photograp ic power 100 110 120 115 112 115 110 Points "Clean Clean Clean Fair Slag Slag Slag The figure of the drawing also shows the effects of varying amounts of the twomaterials, the curve being plotted from the data This curve shows that maximum photographic power is reached when the thorium content is not quite equal to the ra. e earth fluorid content. By referring to the table, it will also be seen that no 'slagging trouble is found up to the point where the two materials are used in about equal proportions.

The thorium content should therefore always be approximately equal to or less than the rare earth fluorid content.

While I prefer to use thorium fluorid, oxy-fluorid, or oxid with rare earth fluorids, it is also permissible to use other compounds such as the nitrate or metallic thorium itself. The fluorid is to be preferred over the oxid on account offthe very extreme non-volatile character of the latter which has a tendency to increase slagging difliculties. Metallic thorium has a .tendency to react with water to produce hydrogen and thorium oxid and for this reason, it is not as good a constituent as the compounds mentioned.

The rare earth fluorids are fiuorids of such elements as occur in the l/Velsbach residue after the extraction of the thorium. The most common of these elements are cerium, lanthium, neodymium, praseodymium, yttrium and ytterbi-um.

The preceding compounds can be used in either cored, solid trode "for use With either alternating or direct current. The data in the preceding table is taken from tests with cored carbons,

but is given merely by Way of example.

Having described my invention, What I claim is:

1. An arc lamp electrode containing rare parts of rare earth or other form of electo 97}- earth fiuorids, a less quantity of thorium material and'a conducting body.

2. An arc lamp electrode containing 6 fiuorids, 4 parts or "less thorium material and a conducting body.

3. An arc lamp electrode containing 6 parts rare earth fluorids, 4 parts or less of 25 thorium fluorid and the conducting body mixed therewith.

4. An arc lamp electrode containing 6 parts rare-earth fluorids, 4 to parts thorium material and a conducting body. 30 In testimony whereof, I hereunto aflix my signature. I

' WILLIAM R. MOTT..

Witnesses:

ARTHUR S. BEMIS,

G. GRovnR. 

